This invention relates generally to bag making machines and, more particularly, to separator/folder mechanisms for separating and folding plastic bags in a bag making operation.
Plastic bags of various types are in widespread use throughout the world. Such bags can be economically manufactured in large quantities from extruded plastic films, and a variety of machines have been developed for automating the bag making process. Every advancement that makes it possible to produce bags with greater speed and efficiency results in greater savings to tile manufacturers and users of plastic bags.
Plastic bags are typically formed from a continous plastic web that can be in the form of a flattened continuous tube or a continuous folded sheet. By forming bottom welds, in the case of a tubular web, or side welds, in the case of a folded web, individual bags are defined. Typically, a perforation adjacent the bottom or side welds allows separation of the individual bags. Until separation, the bags remain strung together in a continuous ribbon.
For a variety of reasons, additional processing is often necessary before tile bags can, as a practical matter, be offered for sale. For example, a typical run of bags may include far more bags than any one consumer could possible require at one time. In addition, the need to separate the bags manually could detract from the bags' convenience and overall utility. Finally, in the case of larger bags, such as lawn and trash bags, the sheer size of each bag makes handling and packaging difficult unless the bags are first folded down to a more manageable size. Accordingly, a variety of machines have been developed for automatically separating, folding and stacking plastic bags formed from continuous plastic webs.
In one prior machine, bag separation was accomplished by operating a downstream set of nip or separation rollers at a higher speed that an upstream set of rollers. As the perforated web encountered the downstream separation rollers, the higher speed of the rollers pulled the web, thereby tearing it along the perforations. A pneumatic cylinder periodically cycled the high speed separation rollers into contact with each other to initiate the separating sequence. Although effective, the use of a pneumatic cylinder to cycle the separation rollers limited the maximum machine operating speed and caused inaccuracies in the separation spacing.
In one prior machine, a plurality of rope belts were used to convey the separated bags between the separating nip rolls and a number of downstream folding stations. During operation, it was not uncommon for the side edge of a bag to wrap itself around one of tile ropes. This caused jams and required that the machine be shut down while the jam was cleared. Valuable production time could thus be lost.
In view of the foregoing, it is a general object of the present invention to provide a new and improved machine for separating and folding articles formed from a continuous plastic web.
It is a further object of the present invention to provide a new and improved separating and folding apparatus that can perform separations with accuracy at high speeds.
It is a still further object of the present invention to provide a new and improved separating and folding mechanism that can handle a variety of product widths without frequent jamming.